I've only used G1 of the two mentioned.
I'm a very diligent person, but it's completely possible to mess up application of G1.
Basically the only issues you need to avoid is over curing the product, and also ensuring that you thoroughly remove it using G2 residue remover.
You should also have some 99.9% IPA on hand as G2 is essentially IPA (but from my understanding it's tweaked slightly with something).

The one and only time I messed it up I let it over cure, so removal with G2 wouldn't have done it at that point. I ended up machine polishing it off a few weeks later with Carpro Ceriglass and a Rayon pad. Lesson learnt.

Conclusion: G1 is amazing, just be careful with application and removal.

Another here for Nanolex urban, easy to apply/remove, performs well, ive had 12 months out of a single application on my B5 Audi,
good prep is the key, if you skrimp on the prep dont expect any of them to perform and last well,G1 is good but application can be a ballache if you are pushed for time etc.